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Biomedical subjects

S Jern

Publications and source records attributed to S Jern.

At least 73 records · Page 4Linked to original sources
PubMed1995

Enhanced pressor responses to experimental and daily-life stress in borderline hypertension.

OBJECTIVE: It has been suggested that the blood pressure elevation in borderline hypertension is caused by hyperreactivity to stress. We addressed the questions: are subjects with borderline hypertension hyperreactive to mental stress, and, if so, is this reflected in greater blood pressure responses during daily-life activities, and does non-specific pressor amplification by structural vascular changes contribute to reactivity changes? METHODS: Standardized mental stress was performed during invasive monitoring in 54 borderline hypertensive subjects [systolic blood pressure (SBP) 140-160 or diastolic blood pressure (DBP) 84-95 mmHg, or both] and 20 normotensive control subjects (110-130/60-80 mmHg). Sixteen borderline hypertensive subjects had a cardiac index greater than the mean + 1SD of the normotensive control group (hyperkinetic subgroup) and 38 borderline hypertensive subjects had a cardiac index below that level (normokinetic subgroup). Minimal vascular resistance in the forearm and calf was assessed by plethysmography. Ambulatory 24-h blood pressure was recorded. RESULTS: Subjects with hyperkinetic borderline hypertension had similar intra-arterial blood pressure levels to normokinetic borderline hypertensive subjects. Total peripheral resistance was lower in hyperkinetic borderline hypertensive than in normokinetic borderline hypertensive or normotensive control subjects. Hyperkinetic borderline hypertensive subjects had a significantly lower forearm minimal vascular resistance than normokinetic borderline hypertensive subjects. SBP and mean arterial blood pressure responses to stress were augmented in both borderline hypertensive subgroups. Hyperkinetic borderline hypertensive subjects also showed diastolic hyperreactivity in response to mental stress, in comparison both with normokinetic borderline hypertensive and with normotensive control subjects. During ambulatory blood pressure recording, hyperkinetic borderline hypertensive subjects had greater DBP and mean blood pressure increases from night to day than normotensive control and normokinetic borderline hypertensive subjects. CONCLUSION: Borderline hypertension is characterized by pressor hyperreactivity to mental stress. In hyperkinetic borderline hypertensive subjects, stress hyperresponsiveness is also reflected by greater night-to-day blood pressure gradients during 24-h monitoring. Pressor hyperreactivity in hyperkinetic borderline hypertension is not explained by structural changes in the calf or forearm vasculature.

Adolescent↗
PubMed1994

Influence of increased adrenergic activity and magnesium depletion on cardiac rhythm in alcohol withdrawal.

OBJECTIVE: To investigate the prevalence of arrhythmias in alcoholic men during detoxification and its relation to neuroendocrine activation and electrolyte disturbances. DESIGN: Consecutive case-control study. SETTING: Primary and secondary care, detoxification ward. PATIENTS AND CONTROLS: 19 otherwise healthy alcoholic men (DSM-III-R) with withdrawal symptoms necessitating detoxification in hospital. 19 age matched, healthy non-alcoholic men as controls for Holter recordings. INTERVENTIONS: Treatment with chlomethiazole; additional treatment with carbamazepine in patients with previous seizures. MAIN OUTCOME MEASURES: Computer based analyses of mean heart rate and arrhythmias from 24 hour Holter recordings, 24 hour urinary excretion of adrenaline and noradrenaline, magnesium retention measured by means of intravenous loading test, and serum concentrations of electrolytes. RESULTS: The 24 hour mean heart rate was higher in the alcoholic men (97.4 beats/minute, 95% confidence interval (CI) 91.2 to 103.6) than in the controls (69.6 beats/minute, 95% CI 65.4 to 73.8, P < 0.001). However, there was no difference in diurnal heart rate variation. The prevalence of premature supraventricular depolarisations was lower in the alcoholic men (P < 0.05). Neither atrial fibrillation nor malignant ventricular arrhythmias occurred. The sinus tachycardia in the alcoholic men correlated with the concomitant urinary excretion of catecholamines (P < 0.05). The mean serum magnesium concentration was 0.78 mmol/l (95% CI 0.73 to 0.83) in the alcoholic men and 0.83 mmol/l (95% CI 0.81 to 0.85) in a reference population of 55 men aged 40. Magnesium depletion (defined as magnesium retention > 30%) was detected in 10 alcoholic men (53%). Three alcoholic men had serum potassium concentrations < or = 3.3 mmol/l on admission. CONCLUSION: Increased adrenergic activity, magnesium depletion, and hypokalaemia are often seen after heavy drinking, but in alcoholic men without clinical heart disease these changes were not accompanied by arrhythmias other than sinus tachycardia during detoxification in hospital.

Adult↗
PubMed1994

Effects of insulin on vascular responses to mental stress and norepinephrine in human forearm.

Essential hypertension is frequently associated with insulin resistance and hyperinsulinemia. In vitro, insulin has vasodilator actions, but its possible hemodynamic effect on muscular vascular beds in humans is a matter of controversy. We investigated the effects of local hyperinsulinemia on the vascular responses to norepinephrine and physiological vasodilation during mental stress in the perfused-forearm model. Nine glucose-tolerant, normotensive, nonobese men (aged 22 to 36 years) participated. Forearm perfusion studies (venous occlusion plethysmography) were performed during randomized, double-blind intrabrachial artery infusions of insulin (to raise plasma insulin 100 microU/mL) or placebo for 2 hours. A mental stress test and stepwise intra-arterial infusion of norepinephrine (6 to 1200 ng/min) were performed during each infusion. Insulin infusion increased venous plasma insulin to 98.4 microU/mL and increased net glucose uptake threefold. Insulin had a gradual vasodilator effect (P < .05 by ANOVA), and after 90 minutes blood flow was 36 percent units higher relative to the control arm than during placebo (P = .005). During mental stress, forearm blood flow increased by 81% (t test, P = .006) and 92% (P = .01) in the study arm during insulin and placebo infusions, respectively (insulin versus placebo, P = NS). An increased forearm blood flow was maintained throughout the mental stress test during insulin infusion (ANOVA, P = .03). Forearm glucose uptake increased during stress, reflecting forearm hyperperfusion since fractional glucose extraction was unaffected by stress. The increased blood flow was maintained throughout the five norepinephrine dose steps (ANOVA, P < .04).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessels↗
PubMed1994

In vivo release of tissue-type plasminogen activator across the human forearm during mental stress.

We have previously shown that plasma levels of endothelium-derived tissue-type plasminogen activator (t-PA) increase during mental stress. The aim of the study was to investigate in vivo release in an intact human muscle vascular bed. Eleven healthy young males (22-36 yrs) were studied at rest and during 10 min of mental stress (forced arithmetic). Net release or uptake were assessed by arterio-venous (AV) concentration gradients across the forearm of t-PA antigen and t-PA activity, and plasminogen activator inhibitor antigen type 1 (PAI-1). Forearm blood flow was measured by venous occlusion plethysmography. At rest, there was a positive AV-difference of t-PA activity across the forearm indicating a net release of t-PA activity of approximately 3.7 fmol x min-1 x 100 ml-1 (Wilcoxon's signed rank test vs 0, p = 0.01). However, t-PA antigen showed a variable release pattern. On the average, there was a net release of 0.17 ng x min-1 x 100 ml-1 after 60 min of rest (Wilcoxon vs 0, p = 0.07). PAI-1 antigen showed net release at rest. In response to stress, forearm blood flow increased from 1.9 to 2.9 ml x min-1 x 100 ml-1 (ANOVA, p = 0.007), and net release of t-PA activity increased to 9.8 fmol x min-1 x 100 ml-1 (ANOVA, p = 0.01 compared with rest). Arterial and venous plasma t-PA levels also increased significantly during stress (ANOVA, p < 0.01). t-PA antigen showed a similar but less pronounced release pattern during stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Influence of daily-life activation on pulse rate and blood pressure changes during the menstrual cycle.

The aim of the present study was to evaluate the influence of endogenous cyclic changes in female sex hormones during the complete normal menstrual cycle on the daily-life activation of blood pressure and pulse rate. Sixteen normotensive women were investigated daily in the morning during strict bed rest and in the evening after normal daily activities throughout two complete menstrual cycles. Analysis of variance revealed a significant change in morning temperature during the menstrual cycle (P < 0.001), with a raise after midcycle. There was no significant variation in body weight during the cycle. Resting pulse rate increased by 1.7 beats/min from follicular (days 2-8) to luteal (days 20-26) phase in morning recordings (P < 0.01) and by 2.9 beats/min in evening recordings (P < 0.001). Pulse pressure was 2.7 mmHg and systolic blood pressure 3.9 mmHg higher in the evening compared with the morning readings (P < 0.05 for both) in the luteal phase, but were similar in the follicular phase. The influence of daily-life activation on pulse rate and systolic blood pressure, defined as the difference between morning and evening levels, was significantly greater in the luteal phase compared with the follicular phase (delta 1.3 beats/min, P < 0.05 and delta 3.0 mmHg, P < 0.05, respectively). In the present study we find evidence of an altered response in haemodynamic recordings to environmental stress during the menstrual cycle. This interpretation is supported by previous findings of increased responses to experimental stress and extends these observations to naturally occurring stress in daily-life.

Adolescent↗
PubMed1994

Safety aspects of spinal cord stimulation in severe angina pectoris.

BACKGROUND: Spinal cord stimulation has been used over the past decade for the treatment of patients suffering from intractable angina pectoris, despite having received optimal medical therapy, and who are unsuitable for further surgical intervention. The clinical results are promising and several studies have shown that the antianginal effect of the treatment is associated with a reduction in myocardial ischemia. It has been suggested, however, that spinal cord stimulation may only attenuate the transmission of pain from the heart, without influencing myocardial ischemia. This is a major safety concern when applying this treatment strategy. METHODS: The aim of this study was to assess the potentially unfavourable aspects of spinal cord stimulation in patients with severe coronary artery disease and angina pectoris by means of repeated long-term ECG recordings. Nineteen patients who had been accepted for implantation of spinal cord stimulators for the treatment of severe angina pectoris were included. RESULTS: No increases were noted in the frequency of ischemic episodes, the total ischemic burden, or the number of arrhythmic episodes during treatment. CONCLUSION: The results of this study do not indicate any unfavourable effects of spinal cord stimulation in severe angina pectoris in terms of an increase in the frequency or severity of myocardial ischemia during treatment with spinal cord stimulation.

Aged↗
PubMed1994

Release of tissue-type plasminogen activator in response to muscarinic receptor stimulation in human forearm.

We have recently shown that mental stress increases local net release of tissue-type plasminogen activator (t-PA) across the forearm vascular bed. However, the mechanisms responsible for the t-PA release in man during stress are undefined. To study the effects of endothelial cell receptor stimulation and fluid shear stress we used the perfused forearm model to characterize the in vivo tissue plasminogen activator (t-PA) response in man to methacholine (Mch) and sodium nitroprusside (SNP), at doses calculated to cause similar degrees of vasodilation. The study was performed in 7 healthy young men (age 22-24 yrs) without hypertension, diabetes mellitus, or hypercholesterolemia. Each subject received double-blind step-wise i. a. infusions of Mch (0.1-0.8-4.0 micrograms/min) and SNP (0.5-2.5-10 micrograms/min) in randomized order. Each dose step was infused for 5 min. Forearm blood flow was assessed by plethysmography. Net release/uptake was expressed as the product of arterio-venous concentration gradient and forearm plasma flow. At pre-infusion baseline, there was a significant net release of t-PA antigen of approximately 0.9 ng x min-1 x 100 ml-1 and t-PA activity of 3.5 fmol x min-1 x 100 ml-1 across the forearm. I.a. infusion of Mch and SNP increased forearm blood flow from 1.9 to 14.9 and from 1.8 to 12.1 ml x min-1 x 100 ml-1, respectively (Mch vs SBP N.S.).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Borderline hypertension. A 24-hour abnormality.

It has recently been questioned whether borderline hypertension (BH) is a reality or just an artefact due to the person's knowledge of his or her raised blood pressure. This issue was evaluated by measuring ambulatory blood pressure (ABP) in subjects with BH, compared to normotensive individuals (NC). In particular, we wanted to investigate whether the basal blood pressure levels during sleep at night were elevated in BH subjects, or whether these individuals would normalize blood pressure during periods of low psychological arousal. Twenty-four-hour ABP was measured using the Spacelabs monitor 90202. Forty-nine BH subjects (systolic blood pressure [SBP] 140 to 160 mm Hg or diastolic blood pressure [DBP] 85 to 95 mm Hg) and 18 NC (SBP 110 to 130 mm Hg and DBP 60 to 80 mm Hg) were recruited from an unbiased population sample (age 20 to 28 years). The classification of BH and NC, respectively, was confirmed by intraarterial BP recordings. There was the expected variation of blood pressure throughout the 24 h (the highest values in the afternoon and lowest at night). SBP was significantly higher in the BH than in the NC group for the entire 24 h as well as during the four 6-h periods (morning P = .007, afternoon P < .001, evening P < .001, and night P = .025). A smaller but significant difference between the groups was seen for DBP but only in the afternoon and in the evening (morning P = .167, afternoon P = .022, evening P = .038, night P = .310).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Interrelation of cardiac and vascular structure in young men with borderline hypertension.

It is not established whether left ventricular hypertrophy and structural vascular changes are primary phenomena or secondary consequences of raised blood pressure. In this study we investigated 54 borderline hypertensive men (BH) (SBP 140-160 mmHg and/or DBP 84-95 mmHg) and 20 normotensive men (NC) (SBP 110-130 mmHg and DBP 60-80 mmHg), recruited from an unbiased population sample (age 20 +/- 2 years). Blood pressure (BP) levels were confirmed by i.a. BP recordings. Left ventricular mass (LVM) was determined with M-mode echocardiography and minimal vascular resistance (Rmin) was calculated from the blood flow in the calf and forearm after maximal ischaemic work. Central haemodynamics were assessed by intra-arterial blood pressure recordings and cardiac output determinations by the dye dilution technique. In the BH group, LVM and Rmin were strongly correlated to body size, especially weight and body surface area. However, LVM and Rmin were only weakly correlated to blood pressure. In the normokinetic BH subgroup (NBH) (n = 38) minimal forearm vascular resistance was significantly higher than in the hyperkinetic BH individuals (HBH) (n = 16), indicating the presence of structural vascular changes in the former. Furthermore, in the NBH group there was a significant correlation between LVM and Rmin both in the calf (r = 0.490 P = 0.002) and in the forearm (r = 0.520 P = 0.001). This association remained after correction for body size. No such correlation was seen in the HBH subgroup or in the NC group. The present study does give long-reaching conclusions as regards the aetiological factors underlying the cardiovascular remodelling. However, our data show that (1) cardiovascular changes appear early in the course of blood pressure elevation, (2) the cardiac and vascular changes develop in parallel, and (3) structural remodelling is not solely explained by the degree of blood pressure elevation since blood pressure was similar in the two BH subgroups. Thus, other factors than blood pressure appear to be important determinants of structural adaptation in mildly hypertensive states.

Adolescent↗
PubMed1993

Electrocardiographic signs of coronary heart disease in a "low risk" population in rural Crete.

BACKGROUND: Ischemic heart disease (IHD) has been shown to be very uncommon in the population of Crete. Therefore, we established a research project in a rural part of Crete to survey the cardiovascular risk profile and follow the incidence of cardiovascular disease over time. This study investigated the prevalence of ECG abnormalities in the population of five villages and compared the prevalence of hypertension, obesity, diabetes, and hypercholesterolemia in those with and without ECG signs of IHD. METHODS: A cross-sectional study was conducted in a group from 15 to 79 years of age (n = 1218); overall attendance was 926 (76%). Studies included case history, clinical status, laboratory variables, and 12-lead ECG. Technically acceptable ECGs were read and coded blindly for 895 subjects (97%). RESULTS: Minnesota codes suggesting "Probable IHD" were recorded in 3.3% of the women and 3.5% of the men from 45 to 79 years of age. Hypertension was more common in subjects with than in those without "Probable IHD." This also tended to be the case for diabetes. Cholesterol and body mass index were relatively high in both groups. CONCLUSIONS: The present prevalence of "Probable IHD" in Cretans appears to be very similar to that observed in other population surveys. Also, the contemporary cardiovascular risk factor profile in the population was quite unfavorable, with a relatively high prevalence of smoking, dyslipidemia, hypertension, and diabetes. The prevalence of "Probable IHD" was lowest in the village where the health center was situated (1% vs 4.5%), and this difference was also reflected in differences among the villages of some important risk factors for IHD as well as in the way patients with hypertension and other diseases were cared for. Thus, it seems IHD is becoming more prevalent in the "low risk" population of Crete. This may very well be a result of a more unfavorable lifestyle and a higher rate of risk factors than before.

Adolescent↗
PubMed1993

Correspondence between screening and intra-arterial blood pressures in young men with borderline hypertension.

OBJECTIVES: To evaluate the screening blood pressure (BP) for identification of individuals with a mild but persistent elevation of BP referred to as borderline hypertension (BH). DESIGN: Based on screening data from approximately 10,500 men at a military enlistment centre in 1987; an unbiased population sample of young men were recruited. Blood pressure follow-up and investigation of anthropometric and metabolic data were made at Ostra Hospital. SUBJECTS: Men aged 19.8 years (range 17-28) were screened. Three hundred and six were found to have elevated BP (systolic BP (SBP) > 145 mmHg and/or diastolic BP (DBP) > or = 85 mmHg). Of these, 179 were re-examined after 1-3 years, by which time three individuals exceeded the limits for established hypertension and 80 fulfilled the BP criteria for BH (in two out of two blood pressure measurements). Fifty-four of these BH individuals were investigated with intra-arterial (i.a.) BP measurements. A normotensive control (NC) group (SBP 110-130 and DBP 60-80 mmHg; n = 20) from the same population was examined concomitantly. RESULTS: At screening, at the 2-year clinic follow-up and again during the intra-arterial recording, SBP was significantly different in BH vs. NC. With DBP an increasing difference between the groups was observed with time. There were highly significant correlations between screening and 2-year clinic BP (r = 0.72, P < 0.001; n = 74) and screening and i.a. BP (r = 0.57, P < 0.001; n = 74). CONCLUSIONS: These data show that there is a correspondence between BP at the screening procedure and i.a. BP measured 2 years later, indicating that the screening procedure is a useful way of identifying young men with mild but persistent BP elevation. This interpretation is supported by metabolic and biochemical differences between the groups.

Adolescent↗
PubMed1993

Changes in the QRS segment during exercise: effects of acute beta-blockade with propranolol.

Changes in the QRS complex during exercise may provide information with respect to ischaemic heart disease. The intention with present investigation was to shed light on mechanisms behind QRS changes and to study the possibly confounding effects of beta-blockade on such alterations with exercise. Placebo or propranolol respectively was infused in randomized and double-blinded order in seven young healthy men before a maximum exercise test. Advanced computerized vectorcardiography and impedance cardiography was recorded continuously together with blood pressures and blood samples. The Y-lead magnitude increased significantly with propranolol infusion (P < 0.05), but it tended to decrease in the Z-lead (P < 0.07). While the serum potassium concentrations increased (P < 0.0005), the spatial QRS magnitude tended to decrease irrespective of treatment (P < 0.07). These changes correlated with changes in QR-duration (adj r2 > 0.58). With exercise, the mean spatial QRS magnitude decreased with similar amounts irrespective of treatment. However, propranolol made the magnitude decrease earlier (P < 0.01). No effect of treatment was detected on the decrease in QRS-duration. Immediately after exercise, the QRS complex continued to change as during exercise in the placebo investigations, but did not with propranolol (P < 0.05). These different patterns were most obvious in the first half of the QRS complex in the Y-lead. It is concluded that acute beta-blockade modifies QRS alterations both during and after exercise in healthy subjects. This indicates that such drugs may have confounding effects in evaluations of the diagnostic value of QRS alterations.

Adult↗